Method of denicotinizing tobacco



Nov. 15,1938. F, BERKA T A 2,136,485

METHOD OF DENICOTINIZING TOBACCO Filed March l'T, 1936 v s Sheets-Sheet 5 Patented Nov. 15, 1938 UNITED s'rprres PATENT OFFICE Application March 17, 1936, Serial No. 69,320

In Austria February 18, 1936 6 Claims.

- This invention relates to the denicotinizing of tobacco, and provides improved method of accomplishing this end. i

Hitherto tobacco has been denicotinized by the passing of superheated steam and air therethrough. With this method, in order to break down the nicotine salts it is necessary to employ a temperature varying according to the nature of the tobacco used, between about 120 and 160 C. Such relatively high temperature has a deleterious influence on some kinds of tobacco, and more particularly on those of light color, since it gives rise to darkening of the color. In consequence ofthis fact it has often been the practice hitherto to denicotinize light colored tobaccos uneconomically by extraction.

It has also already been proposed to subject tobacco, before extraction by means of nicotinedissolving liquids, to treatment with ammoniated steam containing carbon dioxide, in order to inhibit the occurrence of undesirable oxidation effects, and more particularly darkening of the leaves.

It 'is also known to treat tobacco with a stream consisting of a mixture of gaseous ammonia and steam first of all in a container capable of airtight closure, in order to disengage the nicotine from its salts, and finally to distil off the nicetine with the aid of steam;

With this latter method the tobacco becomes subjected to extraction by the steam, which brings about undesired alteration in its flavor and appearance. attempts have been made to effect denicotinizing of tobacco by. treatment with ammonia and after-treatment in a stream of carbon dioxide.

' In known methods of this description gaseous ammonia is added in great excess to the steam, so that a special after-treatmentis required to remove all traces of ammonia from the tobacco.

Now We have succeeded in establishing the surprising fact that tobacco can be denicotinlzed to a great extent, without suffering discoloration or loss of aroma, with the use. of but slight quantities of ammonia and steam, provided air be employed in great excess. Preferably suficient steam is added to saturate the air with moisture at the temperature at which the tobacco is treated; r

In our method ammonia is only required in the 'amounttheoretically necessary for the conversion of the nicotine content of the tobacco treated; However, since air is employed in great excess we use in practice two to three times the quantity of ammonia theoretically required In order to avoid these results, I

for the conversion of the nicotine salts present in the tobacco treated, that is to say on an average 200 grams of NH: in 300,000 liters of moisturesaturated air per hour.

For the purposes or our method temperatures under 100 C. are suificient.

The method according to the present invention also differs essentially from known denicotlnizing processes in which alkaline liquids are sprayed on to the tobacco. These methods give rise to the formation of spots and blotches on the tobacco, while at the same time it is not possible at low temperature to obtain the required extent of conversion of the nicotine salts.

In accordance with the present invention air is preferably used in quantities amounting to about two hundred times the volume of thetobacco, per minute. During and after the denicotinizing, the tobacco is subjected to aeration tor the purpose of removing the traces of ammonia.

The method according to the invention is preferably carried out with the aid of apparatusconsisting essentially of a container which is divided by a partition wall into two compartments. Through a common conduit there is blown into these chambers, from below, the reaction mixture consisting of heated air, ammonia, and steam required to effect the denicotinizin while this mixture is drawn off at the top likewise through a common conduit. In the chambers there are provided angle-iron frames for the reception of latticed screens filled with tobacco, these frames being adapted formovement or conveyance in such a manner that each individual screen can be conducted from the one chamber past the inlet aperture or-blower nozzle, and upwards in the second chamber, so that, aided by the circulatory movement of the latticed screens, the reaction mixture effects thorough 'denicotinizing of the tobacco.

A form of construction of apparatus in accordance with the invention is shown, by way of example, in the accompanying drawings, in which:

Fig. 1 is a vertical middle section taken on the line I--I of Fig. 2.

Fig. 1a is a partial perspective view of the conveyor means.

Fig. 2 is a horizontal section taken on the line 11-11 of Fig. 1.

Fig. 3 is a vertical section taken on the line III-III of Fig. 1.

' Fig. 4 is a plan view.

Fig. 5 shows a detail, on an enlarged scale, in

section taken on the line VV of Fig. 4.

Eli

Referring to the drawings, there are provided within the outside walls i of the suitably lagged box-like container two vertical wrought-iron shafts or compartments 2 of rectangular crosssection. The resulting intermediate space 3 is divided by means of a partition 8 into two chambers each of which is provided with a closed airtight door 4. The inner walls of the shafts or compartments 2 are provided with track-like slots 5 (see Fig. 1). Angle-iron frames 8 serve to carry the latticed screens and are provided with rollers I projecting through the slots 5 into the shafts or compartments 2. Conveying means 9 of any conventional type, e. g. endless chains driven by sprocket wheels are housed in the shafts or compartments 2 (see Figs. 2 and 3) to carry the frames 8 in a continuous movement through the chambers. A blow-fan l5 located in the chamber "5 forces the reaction mixture past the heater I2, in which a divided heatingcoil I3 is housed, into the conduit 21 which is divided into two parts by a partition'wall II. The bafiles ill provided in the conduit 21 serve to eiifect uniform distribution 01" the reaction mixture in the chambers, for which purpose they are adjustable from the outside by means of rods 28. The baiiies are a series of plates pivotally mounted so as to turn about their vertical center lines, as indicated in Figs. 1 and 4. The rods 28 are connected to one vertical edge of each plate so that, by pulling the rods out or pushing them in, all of the plates can be turned about their pivots. From the drawing-off conduit 26 there is branched off a U-shaped tube I! which leads down to the blower fan I! (Fig. 5). At the juncture between this U-shaped tube l1 and the conduit 26 there is provided a pivoted damper l8 by which the relative proportions of fresh and circulated air can be controlled during the course of the reaction.

From the conduit 26 there is branched the discharge pipe 20 for the spent reaction mixture.

In the U-tube I! there is provided an inlet l9 through which fresh air can be drawn in. The discharging of the spent reaction mixture is regulated by means of a pivoted damper 2|, and the supply of fresh air by a valve 22. Both of these controlling members canbe operated independently of each other, and can be fixed in any desired position. Just before the aperture or orifice of the passage leading to the suction side of the blower ii there is mounted in the U- shaped tube I! a spraying ring 2! through which the ammonia required for the process is blown in. In the heater i2, between the turns of the coil B, there, is provided a spraying grating l4 through which the necessary steam is supplied.

At the commencement of the process, the conveying mechanism which moves the latticed screens is set in operation, while the damper 2| and the valve 22 are closed. The pivoted damper I8 is fully opened. The air contained in the apparatus is drawn from the space 3 by the blower l5 and forcedin again after traversing the heater i 2. As soon as the required temperature has been reached by this internal circulation, which is automatically regulated by a thermostat 25 built into the conduit 21, steam is fed in through the spraying grid H. The damper 2| and the valve 22 are then opened, the damper i8 set to the required ratio between fresh air and circulated air, and ammonia fed in through the spraying ring 24. The blower fan sucks in fresh air through the inlet II, which becomes mixed with the ammonia introduced through the spraying ring 24, and forces the resulting mixture through the heater i2 in which steam is added to the mixture through the spraying grid H. The spent reaction mixture containing nicotine escapes into the open through the outlet 20, or is partly returned into circulation, according to need, by suitable adjustment of the pivoted damper i8.

We have found it to be essential that the air, ammonia, and steam be intimately commixed on entering the apparatus and before coming in contact with the tobacco. This is effected as described by means of the blower.

In Figure 1 the tobacco is shown moving downwardly on the left side of the apparatus and upwardly on the right side. The arrows in the lower portion of the figure indicate the direction of movement of the gas mixture. This renders it apparent that in one part of the movement of the tobacco the gas mixture moves in the same direction and in another part of the movement of the tobacco the gas mixture moves in the opposite direction of the movement of tobacco. This indicates that a counter-current movement of the gas relative to the tobacco takes place.

We claim:

1. The method of denicotinizing tobacco which consists .in treating tobacco with a gaseous mixture consisting of an excess of moisture-saturated air at a temperature under 100 C. and ammonia in a proportion amounting to approximately 2 to 3 times the quantity theoretically necessary to effect conversion of the nicotine salts contained in the tobacco treated, the air being used at the rate of substantially two hundred times the volume of the tobacco treated, per minute, and any residual ammonia is removed by thorough aeration of the denicotinized tobacco.

2. A method of denicotinizing tobacco which consists in conducting tobacco on a conveyor on the counter-current principle in a tunnel through a reaction mixture consisting of an excess of air at a temperature under 100 C., ammonia in a proportion amounting to approximately two to three times the quantity theoretically necessary to effect conversion of the nicotine salts contained in the tobacco treated, and suflicient steam to saturate the air with moisture.

3. A method of denicotinizing tobacco, which consists in conducting tobacco on a conveyor on the counter-current principle in a tunnel through a reaction mixture consisting of air employed at the rate of approximately two hundred times the volume of the tobacco treated, per minute, ammonia in a proportion amounting to approximately two to three times the quantity theoretically necessary to effect conversion of the nicotine salts contained in the tobacco treated, and suflicient steam to saturate the air with moisture, the said mixture being at a temperature below 100 C.

4. A method of denicotinizing tobacco, which consists in conducting tobacco in reaction chambers, first in counter-current movement through a reaction mixture consisting of an excess of air at a temperature below 100 C., ammonia in a proportion amounting to approximately two to three times the quantity theoretically necessary to effect conversion of the nicotine salts contained in the tobacco treated, and suflicient steam to saturate the air with moisture, then pass the point at which said mixture is admitted to said chambers, and finally in movement parallel to the flow of the said mixture.

. 5. A method of denicotinizing tobacco, which consists in conducting tobacco in reaction chambers, first in counter-current movement through a reaction mixture consisting of air employed at the rate of approximately two hundred times the volume of the tobacco treated, per minute, ammonia in a proportion amounting to approximately two to three times-the quantity theoretically necessary to effect conversion of the nicotine salts contained in the tobacco treated, and suflicient steam to saturate the air with moisture, the said mixture being at a temperabacco.

6. The method of denicotinizingtobacco which consists in treating tobacco with a stream of a gaseous mixture consisting of ammonia in a proportion amounting to approximately two to three times the quantity theoretically necessary to efiect conversion of nicotine salts in the tobacco treated and moisture saturatedfair' at a temperature under 100 C. and in a quantity per 'minute sufliciently exceeding the volume of the tobacco to be treated, to continuously remove any residual ammonia from the denicotinized t0- FRITZ BERKA. ALX. GILLERf 

